How do I see what is using Memory?
Open a Command Prompt window and navigate to the Blender application folder (e.g.  CD "C:\Program Files\Blender Foundation\Blender")

Start Blender with the command blender.exe --debug.

You can now see memory usage by pressing Spacebar and searching for Memory Statistics.  This will produce a detailed list of memory usage in the command window used to open Blender:

total memory len: 46.457 MB
peak memory len: 55.115 MB
slop memory len: 5.271 MB
 ITEMS TOTAL-MiB AVERAGE-KiB TYPE
   223 (  13.936    63.992) subsurf arena
  1498 (   8.520     5.824) BLI_Mempool Chunk
     4 (   5.881  1505.508) CDNormal
    14 (   4.996   365.455) imb_addrectImBuf
     1 (   3.000  3072.000) OCIO GPU 3D LUT
    39 (   0.923    24.242) Chunk buffer
  3779 (   0.914     0.248) PropertyRNA
     1 (   0.874   895.125) CDMloopCol
     2 (   0.750   384.016) eh buckets
...